IF coil broken during shipment. how difficult to repair ? - UK Vintage Radio Repair and Restoration Discussion Forum

georgesgiralt · 10th Nov 2008, 4:10 pm

hi guys !
I've got a stereo decoder from Grundig by post this morning. An old one using an ECC81.
One transformer had it's coil broken from the base, pulling the wires from the support.
Upon close inspection, as there are only two wirings of different colours, I bet I can get the proper wiring.
But, doing so I'll shorten the windings a bit.
Is it difficult to re-solder these thin wires and glue the coil to the base ? Should I complain and ask for "a new one"

What do you think ?
It is shown in the attached picture. It's the coil in the front, at the right of the picture. Just in front of the electrolytic condenser.
Thanks a lot for your help !

Boom · 10th Nov 2008, 5:36 pm

I wouldn't have thought that undoing a turn from a coil of that size (probably 19kHz) to enable it to be soldered back in place would make the slightest difference. Just be careful not to block the hole with glue if there is a slug in the coil former.

Station X · 10th Nov 2008, 5:50 pm

If the supplier is willing to give you a "new" one and you aren't going to incurr costs returning the original, I would certainly ask for a new one. If not you have nothing to lose by trying to fix it. The loss of one or two turns will make little difference. It could easily be compensated for by adjusting the slug or capacitor associated with the coil.

georgesgiralt · 10th Nov 2008, 6:33 pm

Hi !
The main problem I have is that it took me months to find a suitable decoder...
So if i return it, all I can expect is a refund.
As you can see in the wiring the offending transformer is the de-emphasis one (on the lower part of the schematics, between the two ECC81 parts).
Tomorrow, I'll try to have a very close look at the wirings using a high magnification loupe and then I'll take a decision.
Thanks for your help !

Brian R Pateman · 10th Nov 2008, 6:36 pm

I'd go for a repair if I were you Georges.

In that position you won't notice any difference losing a couple of turns.

Good luck,

mickash · 10th Nov 2008, 11:05 pm

Hello Georges

I've repaired similar coils before where the wires have snapped close to the base. What I did was attach a new longer piece of wire to the terminal pin. Then I ran it up to the point of the break and cut to the correct length to meet the break. Scraped a small section of insulation away from both wire ends and soldered them together. The join can be insulated with nail varnish or something similar.

This way means that no turns have to be removed. You might need to pull some wire from the coil just to give yourself enough wire to make the connection but shouldn't really need to loose any.

Michael.

georgesgiralt · 11th Nov 2008, 7:31 pm

Hi !
Mr Murphy has played a bit with this one. The only wire which was cut short at the coil was the inner one, but I was fortunate enough because it happened on the upper coil which is about half the length of the lower one.
It took me a couple of hours to properly remove the plastic tar they used to hold the wiring in place, unwound the coil and rewound it. Time to take dinner and a long break. I think I deserve a beer. Tomorrow I'll glue the coil in place and resolder the wires.
I'll let you know when done how the set stereo plays ;-)
Thanks for your advice ! You gave me the guts to go for a repair.... And I'm confident it will be a success, now !

georgesgiralt · 12th Nov 2008, 9:23 am

Hi !
Night brings another question about this coil :
Of the 4 wires cut I only knows two positions because one of the wire had cut at the coil and not at the solder, so I can devise the other end's pin.
How should I wire the second coil back ? Does it matters to have the winding in one way or another ? Or should I just wire it in any position I like ?
Or am I a bit paranoid here ?
Thanks for your help !

Station X · 12th Nov 2008, 9:47 am

Leave the wires a bit too long and try it both ways. If there is a difference to the sound wire it for the best sound.

georgesgiralt · 12th Nov 2008, 6:23 pm

Hi Graham !
I won't re-wire the coil as the sound is FABULOUS !
I had previously installed an integrated circuit decoder into the set to get the stereo. It suffered heavy treble distortion and this was worse when the signal was maximal and on some radios pushing modulation too far.
I was a bit worried when I turned the set on with the old tube decoder, wondering if the obvious broken coil was the only fault. But it ran for 2 hours flawlessly and the sound is so great ! I can now turn the bass and treble control to the maximum without too much distortion and can tune either station and get a very good sound !
Guys if you've a tube set needing a decoder, search and get it the proper tube device ! Its rewarding ! (and looks way better also)
It was worth the wait and the repair. Thanks a lot for your helps !

10th Nov 2008, 4:10 pm	#1
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	IF coil broken during shipment. how difficult to repair ? hi guys ! I've got a stereo decoder from Grundig by post this morning. An old one using an ECC81. One transformer had it's coil broken from the base, pulling the wires from the support. Upon close inspection, as there are only two wirings of different colours, I bet I can get the proper wiring. But, doing so I'll shorten the windings a bit. Is it difficult to re-solder these thin wires and glue the coil to the base ? Should I complain and ask for "a new one" What do you think ? It is shown in the attached picture. It's the coil in the front, at the right of the picture. Just in front of the electrolytic condenser. Thanks a lot for your help ! Attached Thumbnails

10th Nov 2008, 5:36 pm	#2
Boom Retired Dormant Member Join Date: Jan 2007 Location: Westbury, Wiltshire, UK. Posts: 2,451	Re: IF coil broken during shipment. how difficult to repair ? I wouldn't have thought that undoing a turn from a coil of that size (probably 19kHz) to enable it to be soldered back in place would make the slightest difference. Just be careful not to block the hole with glue if there is a slug in the coil former.

10th Nov 2008, 5:50 pm	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: IF coil broken during shipment. how difficult to repair ? If the supplier is willing to give you a "new" one and you aren't going to incurr costs returning the original, I would certainly ask for a new one. If not you have nothing to lose by trying to fix it. The loss of one or two turns will make little difference. It could easily be compensated for by adjusting the slug or capacitor associated with the coil. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

10th Nov 2008, 6:33 pm	#4
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	Re: IF coil broken during shipment. how difficult to repair ? Hi ! The main problem I have is that it took me months to find a suitable decoder... So if i return it, all I can expect is a refund. As you can see in the wiring the offending transformer is the de-emphasis one (on the lower part of the schematics, between the two ECC81 parts). Tomorrow, I'll try to have a very close look at the wirings using a high magnification loupe and then I'll take a decision. Thanks for your help ! Attached Thumbnails

10th Nov 2008, 6:36 pm	#5
Brian R Pateman Nonode Join Date: Jun 2005 Location: Western Lake District, Cumbria (CA20) - UK Posts: 2,136	Re: IF coil broken during shipment. how difficult to repair ? I'd go for a repair if I were you Georges. In that position you won't notice any difference losing a couple of turns. Good luck, __________________ Brian

10th Nov 2008, 11:05 pm	#6
mickash Hexode Join Date: Sep 2007 Location: Derbyshire, UK. Posts: 289	Re: IF coil broken during shipment. how difficult to repair ? Hello Georges I've repaired similar coils before where the wires have snapped close to the base. What I did was attach a new longer piece of wire to the terminal pin. Then I ran it up to the point of the break and cut to the correct length to meet the break. Scraped a small section of insulation away from both wire ends and soldered them together. The join can be insulated with nail varnish or something similar. This way means that no turns have to be removed. You might need to pull some wire from the coil just to give yourself enough wire to make the connection but shouldn't really need to loose any. Michael.

11th Nov 2008, 7:31 pm	#7
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	Re: IF coil broken during shipment. how difficult to repair ? Hi ! Mr Murphy has played a bit with this one. The only wire which was cut short at the coil was the inner one, but I was fortunate enough because it happened on the upper coil which is about half the length of the lower one. It took me a couple of hours to properly remove the plastic tar they used to hold the wiring in place, unwound the coil and rewound it. Time to take dinner and a long break. I think I deserve a beer. Tomorrow I'll glue the coil in place and resolder the wires. I'll let you know when done how the set stereo plays ;-) Thanks for your advice ! You gave me the guts to go for a repair.... And I'm confident it will be a success, now !

12th Nov 2008, 9:23 am	#8
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	Re: IF coil broken during shipment. how difficult to repair ? Hi ! Night brings another question about this coil : Of the 4 wires cut I only knows two positions because one of the wire had cut at the coil and not at the solder, so I can devise the other end's pin. How should I wire the second coil back ? Does it matters to have the winding in one way or another ? Or should I just wire it in any position I like ? Or am I a bit paranoid here ? Thanks for your help !

12th Nov 2008, 9:47 am	#9
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: IF coil broken during shipment. how difficult to repair ? Leave the wires a bit too long and try it both ways. If there is a difference to the sound wire it for the best sound. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

12th Nov 2008, 6:23 pm	#10
georgesgiralt Hexode Join Date: Jul 2008 Location: Toulouse, France Posts: 406	Re: IF coil broken during shipment. how difficult to repair ? Hi Graham ! I won't re-wire the coil as the sound is FABULOUS ! I had previously installed an integrated circuit decoder into the set to get the stereo. It suffered heavy treble distortion and this was worse when the signal was maximal and on some radios pushing modulation too far. I was a bit worried when I turned the set on with the old tube decoder, wondering if the obvious broken coil was the only fault. But it ran for 2 hours flawlessly and the sound is so great ! I can now turn the bass and treble control to the maximum without too much distortion and can tune either station and get a very good sound ! Guys if you've a tube set needing a decoder, search and get it the proper tube device ! Its rewarding ! (and looks way better also) It was worth the wait and the repair. Thanks a lot for your helps !